A5086821300- Ionosphere and magnetosphere dynamics
- Solar and Space Plasma Dynamics
- Geomagnetism and Paleomagnetism Studies
- Atmospheric Ozone and Climate
- Earthquake Detection and Analysis
- Geophysics and Gravity Measurements
- Astro and Planetary Science
- Atmospheric chemistry and aerosols
- Calibration and Measurement Techniques
- Atmospheric and Environmental Gas Dynamics
- Spectroscopy and Laser Applications
- Plasma Diagnostics and Applications
- Seismic Waves and Analysis
- Meteorological Phenomena and Simulations
- GNSS positioning and interference
- Planetary Science and Exploration
- Methane Hydrates and Related Phenomena
- Magnetic confinement fusion research
- Atmospheric aerosols and clouds
- Ocean Waves and Remote Sensing
- Space Satellite Systems and Control
- Spacecraft Design and Technology
- Laser-induced spectroscopy and plasma
- Adaptive optics and wavefront sensing
- Advanced Control Systems Optimization
University of Calgary
2001-2018
Institute of Terrestrial Magnetism Ionosphere and Radio Wave Propagation
1992
Arecibo Observatory
1971
University of Saskatchewan
1965-1969
Measurements of neutral nitrogen density from mass spectrometers on five satellites (AE-B, Ogo 6, San Marco 3, Aeros A, and AE-C) temperatures inferred incoherent scatter measurements at four ground stations are combined to produce a model thermospheric densities similar the 6 empirical (Hedin et al., 1974). This global is designated MSIS (mass spectrometer scatter). The average temperature, annual temperature variation, lower bound density, discussed. data set covers time period end 1965...
The WIND imaging interferometer (WINDII) was launched on the Upper Atmosphere Research Satellite (UARS) September 12, 1991. This joint project, sponsored by Canadian Space Agency and French Centre National d'Etudes Spatiales, in collaboration with NASA, has responsibility of measuring global wind pattern at top altitude range covered UARS. WINDII measures wind, temperature, emission rate over 80 to 300 km using visible region airglow from these altitudes as a target employing optical Doppler...
In an analysis of 6300‐Å nightglow measurements obtained at Arecibo on the night April 25/26, 1976, Cogger et al. (1980) reported that model estimates exceeded observed intensity by a factor 2. We have reanalyzed data in light newer laboratory and aeronomic determinations parameters used to calculate now obtain agreement with measurements. The rate coefficient for reaction O + 2 → required fit is 27% smaller 700 K than previously assumed, but thermal drift tube Chen (1978). A specific...
Ultralow frequency (1–4 mHz) shear Alfvén, field line resonances are often found in the nightside magnetosphere on lines threading equatorward region of auroral zone. The morphologies electric fields and field‐aligned currents these is very similar to those discrete arcs. This leads possibility that some types arcs might be produced by resonances. would produce with latitudinal scale sizes order 10 km, longitudinal many time zones, periodic restructuring timescales minutes. standing wave...
The Tsyganenko long magnetospheric model (1987) has been used in conjunction with ultraviolet images taken by the Viking spacecraft to investigate relationship of auroral distribution different regions. describes large‐scale structure magnetosphere reasonably well for dipole tilt angles near zero, but it appears break down at higher angles. Even so, a wide variety configurations can be accurately described model. It that open‐closed field line boundary is poor indicator arc systems possible...
The departure of the aurora from quiet levels in a dynamic manner constitutes some type auroral “breakup” event. Research into breakup predates International Geophysical Year (1957/1958). This feature aurora, and later, more global concept substorm, has become focus for much research that occurs today. New instrumentation collaborations continue to refine our knowledge substorm process how it proceeds ionosphere. In particular, imaging advanced understanding dynamics given us ability put...
Multi‐instrument data sets from the ground and satellites at both low high altitude have provided new results concerning substorm onset its source region in magnetosphere. Twenty‐six out of 37 events showed evidence azimuthally spaced auroral forms (AAFs) prior to explosive poleward motion associated with optical onset. The azimuthal wavelengths these onsets were found range between 132 583 km a mean value 307±115 km. occurrence rate increased decreasing wavelength down cutoff near 130 AAFs...
The V5 ultraviolet auroral imager is one of a complement experiments launched into polar orbit aboard the Swedish spacecraft Viking in February 1986. consists two intensified wide‐angle f/1 cameras, identical except passband, with electronic despinning providing exposure times second. Critical to use tapered fiber optic bundles remove distortions generated when spherical focal surface Burch configuration camera projected onto plane charge coupled detector. Data acquired by are telemetered...
Observations of polar cap sun-aligned arcs obtained with the auroral scanning photometer on Isis 2 for period 1971 to 1975 are examined. A 2∶1 asymmetry was found in occurrence frequency between morning and evening sectors cap. Sun-aligned were observed only 0.6% passes occurred most frequently during periods low magnetic activity (Kp AE). Moreover, all cases times which interplanetary field data available, directed northward. Although intensity along any single arc varied considerably, it...
Optical images of the polar cap region at both 5577 and 3914 Å obtained from 1400 km above earth have been used to study relationship between oval aurora during periods when interplanetary magnetic field is strongly northward, i.e., B 2 > 3.5 nT. When this rather rare condition occurs, distinction two types no longer as clear depicted on basis statistical definitions auroral oval. Diffuse, weak emission can fill in discrete features cap. The appear very similar arcs intensity, intensity...
Sun‐aligned arcs are long and sometimes narrow optical structures which oriented in the sun‐earth direction occur polar cap, generally during intervals of low magnetic activity. Their appearance, as seen by DMSP ISIS‐2 satellite photometers, is examined with respect to north‐south orientation interplanetary field. In pictures it found that they appear when IMF directed northward. 16 out 18 unambiguous observations sun‐aligned ISIS‐2, was northward; for other two no data available. These...
Viking images obtained throughout 1986 have been utilized in combination with IMP 8 satellite measurements of the interplanetary magnetic fields (IMF) to determine typical northern hemisphere auroral distributions for a variety IMF B z positive conditions. Varying y has an effect which is consistent expected results. That is, implies high‐latitude arcs dusk sector while negative gives dawn polar arcs. A new result significant importance x component IMF. toward Sun ( = 0) on both and...
Arc widths were calculated for 3126 stable auroral arcs observed by an all‐sky camera located in Gillam, Manitoba. The is filtered to accept 5577‐Å emissions and has a single‐pixel spatial resolution of 1.7 km at zenith. measured mean width mesoscale within ±5° magnetic zenith 18 with standard deviation 9 km. distribution exhibits steep cutoff below 8 km; when combined studies small‐scale structure this suggests gap the occurrence order 1 This feature arc spectrum argues against notion...
Aurora on the dayside of earth observed under especially favorable viewing conditions by scanning auroral photometer ISIS‐2 satellite show several distinctive features. (1) Usually, but not always, a gap or discontinuity in 5577Å aurora is present through 10.5 ‐ 12.5 MLT sector, same region where 6300Å typically reaches maximum. Weak 3914Å emission smoothly fills this most passes. (2) A persistent intensity enhancement occurs between 14 and 16 MLT, which probably related to statistically...
A technique is described whereby wavelength scanning of a Fabry–Perot spectrometer accomplished by varying the angle at which light transmitted through etalon. It in essence simple photoelectric adaptation old photographic method but it has number important advantages. These are pointed out, and descriptions given four instruments been applied. One these hypothetical, one under construction, two have built tested. They all designed primarily for auroral airglow observations, should find use...
During the later stages of auroral substorm luminosity distribution frequently resembles a double oval, one oval lying poleward normal or main UV oval. We interpret morphology as being due to plasma sheet boundary layer becoming active in process. If disturbance engulfs nightside low‐latitude layers, then configuration extends into dayside ionospheric region. The is associated with inner portion central and can rapidly change its character from diffuse discrete. This transition process...
In view of a recent revival interest in the black aurora and related phenomena, striking lack information on phenomenon literature, we present high spatial temporal resolution optical observations made by University Calgary portable auroral imager. A variety such as vortices, arcs, eastward drifting patches arc segments, were observed evening midnight sector diffuse oval during field trip to Rabbit Lake, Saskatchewan, from February 25 March 7, 1995. Observed characteristics are reviewed,...
Optical observations with DE 1 and Viking demonstrate conclusively that transpolar arcs can be present simultaneously at polar latitudes in both hemispheres. The observed here are aligned parallel to one another on opposite sides of the magnetic pole, relative noon‐midnight meridian rotated slightly counterclockwise direction when viewed from above North Pole.
We investigate the two‐dimensional structure of auroral poleward boundary intensifications (PBIs). PBIs are a nightside intensification that has been studied primarily with ground‐based meridian scanning photometers (MSPs). They have signature in MSP data, appears as an increase intensity at or near magnetic separatrix and is often seen to extend equatorward. also associated fast flows tail thus important dynamics plasma sheet. data provide information about temporal evolution aurora one...
Direct measurements of the F region neutral wind field in northern (winter) hemisphere during late November and December 1981 were obtained by using Dynamics Explorer (DE 2) satellite network ground‐based Fabry‐Perot interferometers sited North American Scandinavian sectors. All available data for study period have been collated averaged according to universal time (UT) provide a global‐scale experimental determination mean or average circulation region. The are organized into UT “bins”...
From 32 000 [O1] 5577 Å airglow limb observations made between April 1971 and December 1972 from the ISIS-2 satellite, major temporal spatial night features have been identified. Two methods of analysis were employed: harmonic fitting global correlation. Airglow emission rate maxima occurred in mid-October mid-April at all latitudes. The intensities peaked near 35° winter 25° summer showed a symmetry with latitude centred about 5° hemisphere. mean intensity mid-latitudes was 175 R equator...
The latitude dependence of the changes in ionosphere total electron content (TEC) has been studied during 12 magnetic storms. TEC observations were obtained at Hamilton, Massachusetts, and Arecibo, Puerto Rico. Definite differences are observed responses storms: both enhancements depletions while only measured Arecibo. A pre-local midnight ‘ledge’ is frequently Arecibo storm data but seldom higher-latitude Hamilton data. These enhanced ledges TEC, together with nighttime produce large...